The present invention generally relates to floorcoverings or floor covering having an electric heater built therein and, more particularly, to an improvement of the safety of the floorcoverings having a built-in heater.
A carpet, mat or pad having an electric heater built therein is well known. The heater embedded in, for example, a carpet, is a planar heater in the form of either one or a combination of one or more heating wires and one or more film heaters and is generally distributed over the surface of the carpet. One example of prior art heating carpet is shown in partial sectional representation in FIG. 1 of the accompanying drawings.
Referring to FIG. 1, the prior art heating carpet is generally of a planar sandwich structure including an underlining layer 1 of heat insulating material, a continuous electrically insulated heating wire 2 placed immovable on one surface of the underlining layer 1 so as to extend in a generally zig-zag-shaped configuration, a metallic foil 3 placed on said one surface of the underlining layer 1 so as to cover the heating wire 2 for the uniform distribution of heat produced by the heating wire 2, and a surfacing layer 4 of any suitable material, for example, textile fabric, placed on the metallic foil 3. The opposite ends of the heating wire 2 are drawn into a box secured to a portion of the peripheral edge, or a corner area, of the carpet and are secured to respective plug pins through a controller in the box.
With the prior art heating carpet, it has been found that, when a needle or the like is inadvertently or accidentally pierced into the carpet with its tip contacting the heating wire 2 during the operation and when someone subsequently happens to touch such needle, he or she will receive an electric shock.